The well-muscled Michaels has described herself as a formerly overweight, unhappy youngster who found a path to fitness through martial arts, eventually becoming a trainer, physical therapy aide and then sports-medicine professional.

In 2012, Michaels returned for the show's 14th edition after taking a break to pursue adoption of a daughter. She and her partner also have a son.

"The Biggest Loser" provoked a debate in February when contestant Rachel Frederickson won after a huge weight drop that took her from 260 to 105 pounds. Criticism arose on social media about whether she'd lost too much, while experts questioned the focus on body size rather than overall health.